For a number of years in the field of transplanting organs from one body to another, efforts have been made to store such organs, particularly kidneys, experimentally with dogs for illustration, and to subsequently transplant the organ into the same or different animal. Heretofore, most attempts undertaken to freeze organs and in particular kidneys, for transplantation have been unsuccessful. Subsequent to excising or removing by surgical procedure a kideny, such as from a dog, there has been an initial step of flushing the kidney with flushing solutions and thereafter subjecting the kidney to perfusion with plasma-like substances and chemicals referred to as cryoprotective agents and thereafter freezing the kidney. Subsequent to freezing for a predetermined interval at a predetermined temperature, the kidney has been thawed within a suitable oven and thereafter subjected to a second hypothermic pulsatile perfusion to remove from the kidney the cryoprotective agent. Thereafter as a final step, the kidney is transplanted into an animal.
To date there has been multiple efforts in this process, most of which have been unsuccessful, or if successful only for a very limited period. Difficulties have been involved in the use of cryoprotective agents employed in conventional hypothermic pulsatile perfusion and the subsequent manner of freezing of the organ.
Problems have arisen as to speed at which freezing should occur and final temperatures to be achieved during flushing, during perfusion and during freezing. Further problems have existed in the manner in which the kidney is frozen in time periods, i.e., rate of cooling, whether it be a slow freeze or a fast freeze and the final temperature at which the kidney is maintained. Further, other problems have arisen in the means by which the kidney is thawed, whether it be in a heating area for fast thawing or slow thawing. Finally, another problem relates to the use of hypothermic pulsatile perfusion upon the thawed kidney to remove the cryogenic protective agents all before transplant into the animal.
Heretofore kidneys after exising are flushed with cold (4.degree. C.) heparinized (10,000 u'liter) Ringer's lactate through the renal artery until the venous effluent was clear. Thereafter, the kidney was treated under hypothermic pulsatile perfusion utilizing plasma-like perfusates and certain liquid protective agents as for example DMSO known as Dimethyl Sulfoxide, or Glycerol. Freezing has been practiced after 6 to 24 hours of perfusion with the kidneys placed in a freezing apparatus by metering helium intraarterially through the renal artery flowing at a rate of 1500 cc count per minute approximately. Heretofore, liquid nitrogen was circulated around the helium line cooling the helium for infusion into the renal artery of the kidney. Also the kidney has been chilled down to -85.degree. C. to -120.degree. C., for illustration, over a predetermined period to five or more minutes and thereafter maintained at said temperature for a period of time.
Various techniques have been applied for thawing the frozen kidney utilizing an oven for rapid thawing.
Problems have arisen with the speed at which the kidney was frozen and the temperature at which it was maintained as well as the speed with which the kideny was thawed in the oven, such as a microwave oven. Subsequently, on thawing, the kideny was introduced into a hypothermic pulsatile perfusion apparatus for removing a protective agent and thereafter reimplanted.
While this general method has been tried over a period of years, most efforts have been unsuccessful. This is believed due to lack of knowledge as to the best mode for protecting the organ by the use of perfusion thereinto of protective fluids, the rate of freezing and the extent of freezing.
Various problems have arisen in the lack of uniform thawing of the frozen kidney or other organ or improper or non-uniform thawing or with the rate of thawing not being finally determined as to whether it should be fast throughout or fast initially and slow subsequently up to room temperature. Most of said kidneys have been unsuccessfully transplated back into animals wherein due to the manner of handling and the methods known, the kidney has not performed at proper serum creatinine levels for normalization thereof.